Neutron diffraction study of Nd0.8Tb0.2Mn2O5 single crystal has been performed using both non-polarized and polarized neutron diffraction. Low temperature set of magnetic satellites corresponding to two magnetic ordered phases witnesses about the magnetic phase separation. One of those phases with propagation vector k1 = (0.5 0 kz1) bears features of magnetic order in TbMn2O5 with ordering temperature TN ≈ 37 K. Another one with propagation vector k2 = (0.5 0 kz2) and Neel temperature of TN2 ≈ 30 K has a great similarity to magnetic order of NdMn2O5. Both of them are chiral at low temperatures. Difference in chiral domain population could be controlled by the external electric field of few kV/cm. Two additional magnetic phases with k3,4 = (0.5 0 kz3,4) were observed in the short intermediate temperature range 20 – 28 K. Significant temperature hysteresis of 6-8 K for all magnetic phases was observed in dependence of cooling/heating temperature evolution. Results are discussed in the frame of competing magnetic interactions.